Water has many important functions including regulating temperature, lubricating joints and transporting nutrients and waste throughout the body. Staying hydrated is particularly important during exercise. Adequate fluid intake is essential to comfort, performance and safety. The longer and more intensely you exercise, the more important it is to drink the right kind of fluids.
Because there is wide variability in sweat rates, losses and hydration levels of individuals, it is nearly impossible to provide specific recommendations or guidelines about the type or amount of fluids athletes should consume. Be wary of “studies” and “experts” that tell you exactly how much to drink and when to drink it, as the advice is written for a specific situation and a specific person with a specific body type and athletic ability. If you are planning to walk on the treadmill then take a yoga class, you should not hydrate at the same level as a person planning to run a marathon. Yet, blanket advice is put out there, encouraging an intake of a certain amount of ounces before, during and after a workout. Consider how hard you are exercising, how long you are exercising for , the temperature and humidity of your surroundings, and your Individual body chemistry… if you are 100% sure that the study used a subject is in your exact situation, take the advice, if not, take a moment to re-evaluate the advice.
If, however, you find yourself exercising in extreme conditions over 3 or 5 hours (a marathon, Ironman or ultramarathon, for example) you should consult with a Trainer or medical professional, as your situation may require for you to add a complex sports drink with electrolytes, calories or other formulation to keep you putting out the best performance with the least amount of physical risk.
Exercise heats up your muscles. Your body tries to maintain your regular temperature (around 98 degrees) by sweating. Sweat evaporates and cools the skin. IF your blood is working to turn water into sweat, it is available at a decreased level to aid your working muscles. If you take in water to cool off, your body doesn’t have to do so much work and can concentrate on getting nutrients to the muscles.
When your muscles start exercising, they produce extra heat. This is why exercise makes you feel warmer. Studies have shown that internal body temperature increases at the beginning of exercise, but then maintains throughout the activity- it does not keep escalating. Your body is magical! It will automatically regulate itself to maintain the highest temperature it can sustain. The main method of heat dispersal during exercise is sweating. If sweating isn’t enough, your body will want to slow down, so when you feel fatigue and the need to slow down, do it! Listen to your body….it is smarter than the research you are trying to follow. What’s more, its not trying to sell you something, so you can trust your body when it tells you, “I need water” or “I need to take a break”.
Make sure you are well-hydrated before exercise- don’t start exercising if you are already thirsty- take a few drinks until you feel good, then start exercising. It is clear that if you begin a training session or competition in a dehydrated state your performance will suffer and you will be at a competitive disadvantage.
Consider this: In the 1900’s the advice from medical community and sports experts was to not drink at all before or during exercise, claiming that drinking fluids would dilute balance of nutrients and degrade performance. They also claimed taking in fluids during exercise would cause other physical ailments, including severe cramping, pulled muscles, cramps, dizziness, nausea and heat exhaustion.
Later, in the 1980s, Gatorade conducted a series of heavily publicized studies that happened to have results favoring the purchase of mass quantities of you guessed it…Gatorade! So much advertising and promotion went into these “findings” that the theories changed completely, to reflect the absolute need to drink, drink, drink, ad nauseum. And ad nauseum they did, sometimes falling ill to over hydration.
A compromise of sorts was eventually reached, and the most recent (2007) ACSM position stand on fluid replacement reflects the growing awareness of the dangers of overdrinking. Gone was “the drink as much as tolerable” statement, replaced by the recommendation that one should drink during exercise “to prevent excessive (>2%) dehydration”. In other words, it’s now recognized that if you drink more than you sweat, you’re running into trouble. And 2% dehydration is now defined as an upper limit – 1 to 2% is thus acceptable, which is a significant departure from the previous concepts. The problem is still the dogmatic paradigm with which dehydration is approached – the entire basis is that dehydration is bad, despite a lack of evidence for this attitude.
Basically, drink when you are thirsty. Since you are smart enough to know when you will be engaging in an activity that will make you thirsty, have some water prior to that activity so you don’t suffer unnecessarily by being thirsty! Then drink more as you feel a thirst coming on…
Core temperature is regulated by the ambient temperature and wind speed, not hydration. Work load affects body temperature and need for hydration, not length of activity
In the end, the message is that yes, fluid ingestion can indeed affect your ability to regulate core temperature. However, this effect is overstated and very small, and your body will always protect you by making you slow down before you suffer and major physiological consequences from this.
What we can say now is that when performance is a desirable outcome, you must drink to thirst, for it will optimize the amount of fluid ingestion.
Should you choose to ignore your thirst, you will not collapse from “heat illness,” and nor will you die from heatstroke. However, you will be miserable and you will run slower than you would like.
We hope it has become clear that, for a number of reasons, it is not necessary to drink so much during exercise, and in furthermore no one needs to tell you how much to drink. As we have shown you here, the thirst mechanism is highly sensitive and very successful at what it is meant to do: maintain your osmolality, not your weight. But the final message here is that when you drink to thirst, you optimize your fluid intake, and by that we mean your thirst will always keep you from drinking too much or too little. There is such a thing as both of those, but drinking to thirst will always prevent you from straying too far in one direction or the other.
In addition, who wants to carry around three Liters of fluid in a backpack when half that volume will be just plenty? And when there is no scientific evidence to support the claims that dehydration increases your core temperature or elevates your risk for heat stroke, it seems quite unnecessary
One last thing, is that as humans, we are regarded (by most, anyway) as the smartest animals, right? Yet for some reason, companies making fluids deem it necessary to inform you how much you should drink. Have you ever had to force your pet cat or dog to the water bowl? Have you ever seens signs in the wild pointing animals to the watering hole with instructions to drink before they’re thirsty? Yet somehow, the Gatorades of the world have “discovered” the NEED to educate us all about fluid. It does strike one as patently ridiculous – thirst is good enough for every animal in the world, it’s good enough for us…!